1. Field of the Invention
The present invention relates to a cantilever holder for attachably and detachably fixing a cantilever having a stylus at a front end thereof and a scanning probe microscope having the cantilever holder.
2. Background Art
According to SPM (Scanning Probe Microscope) of a type of using a cantilever of AFM (Atomic Force Microscope) or the like, in order to use an optimum cantilever in accordance with a sample, the cantilever is attachably and detachably fixed to and from a cantilever holder and is made to be able to be interchanged. In order to fix the cantilever to the cantilever holder, normally, a main body portion for supporting a base end side of the cantilever in a single-held state is set to an attaching portion of the cantilever holder, and the main body portion is fixed to the attaching portion by being held by various holding members.
Although various holding members have been proposed, normally, a wire (refer to, for example, JP-A-2003-121335) or a leaf spring (refer to, for example, JP-A-2000-249714) is adopted. Further, generally, a metal material is used for the wire or the leaf spring to ensure to be fixed to the cantilever.
However, according to the above-described cantilever holder of the related arts, the following problem is posed.
That is, in SPM, in order to further diversely observe a sample, various measuring modes are prepared, and an observer observes the sample by selecting an optimum measuring mode in accordance with an object thereof.
For example, there is an AC mode AFM for oscillating a cantilever by a predetermined frequency (resonance frequency or a vicinity thereof) and carrying out scanning while controlling a distance between the stylus and the sample to be constant.
In carrying out measurement by the AC mode AFM, there is a case in which a main body portion cannot firmly be fixed by the cantilever holder of the related art, as a result, there is a case in which an influence is effected on oscillating the cantilever by a predetermined frequency.
That is, although according to the method of fixing the cantilever by utilizing the wire, as shown by, for example, FIGS. 11A and 11B, a main body portion 4 is pressed to a cantilever holder 2 by a wire 43, since the wire 43 is a wire member made by a metal and having a hardness, there is a case in which the wire is not deformed along an outer shape of the cantilever holder 2 to bring about a state in which the wire is brought into contact with two points of both ends of the main body portion 4. Therefore, in this case, the main body portion 4 cannot be firmly fixed by being pressed to the cantilever holder 2.
Further, although according to the method of fixing the cantilever by utilizing the leaf spring, it seems that the cantilever is fixed in a state of apparently bringing the leaf spring and the main body portion into face contact with each other, surfaces of the leaf spring and the main body portion are constituted by shapes of small recesses and projections and therefore, there is a case in which the leaf spring and the main body portion are brought into a point contact state similar to the case of the fixing method utilizing the wire. In this case, multipoints contact is produced and therefore, the fixing becomes more solid than that in the two points contact in the fixing method utilizing the wire, however, it is invariably difficult to fix firmly the main body portion.
In this way, according to the methods of the related arts, the main body portion cannot firmly be fixed and therefore, in accordance with oscillation of the cantilever, also the main body portion is oscillated. Therefore, an influence is effected on a state of oscillating the cantilever and the cantilever cannot be oscillated by a predetermined frequency.
Further, there is a case in which oscillation of the cantilever holder is transmitted to the main body portion, also in this case, the main body portion is oscillated by the transmitted oscillation and the oscillation is further transmitted to the cantilever. That is, the main body portion is not firmly fixed and therefore, oscillation of the cantilever holder is transmitted to the cantilever by way of the main body portion and the cantilever cannot be oscillated by the predetermined frequency.
Therefore, in measuring a Q curve (resonance characteristic curve for determining an optimum value (operating point) of an oscillating frequency), an influence is effected on measurement (for example, a resonance point is shifted, a magnitude of an oscillation amplitude is changed or the like) to bring about a drawback that the Q curve cannot stably be measured. As a result, measurement by the AC mode AFM cannot accurately be carried out.